Friday, December 20, 2013

How to grow and re-bloom poinsettias

JPinching them back, giving them good sunlight and a night rest in the fall are the keys to re-blooming the signature plant of Christmas.

Dec 29 2011

Year in and year out, Americans buy more poinsettias than any other type of flowering indoor potted plant. Last year, for example, 36.1 million pots of poinsettias with a wholesale value of $146.1 million were sold in the United States, according to the USDA Floriculture Crops 2010 Summary. 

Sales of spring flowering bulbs were a distant second at 22.5 million pots with a wholesale value of $59.8 million, according to the same report. Orchids were third in pots sold at 21.1 million, but, interestingly, had the highest wholesale value, $170.1 million. No other indoor flowering plant — Easter Lillies, African violets, florist chrysanthemums, azaleas or roses — came close to poinsettias in either number of pots sold or value.

After the holidays, what are homeowners to do with all of those poinsettias?

Many will throw them away. However, with proper care, poinsettias can be grown as perennials in outdoor gardens in frost-free areas or as house plants elsewhere.

Here is a guide to keeping your poinsettia fresh during the holidays and to re-blooming it next Christmas.

Holidays, winter
Place the plant in a sunny room but avoid areas with cold drafts or excessive heat. When the soil is dry to the touch, take the plant to the kitchen sink, remove any decorative wraps and water it until the water drains through the bottom of the pot. Do not let the plant sit in water and do not fertilize it while it is in flower.

In March or April, cut the plant back to about eight inches high. Water regularly, keeping the soil moist but not soggy. Fertilize once a month with a balanced, all-purpose fertilizer. By the end of May, the plant should be growing vigorously. Be aware that in its native habitat of Mexico and Central America the poinsettia (Euphorbia pulcherrima) can grow as large as a small tree, up to 16 feet tall.

In early June, re-pot your plant in a larger pot, but make sure the new pot is no more than four inches wider than the original pot. Use a potting mix high in organic matter, such as peat moss. In frost-free zones, it can be transplanted into the garden. Best results will be obtained in a bed rich in organic matter that has good drainage and receives strong sunlight.

For potted plants, place outdoors in a bright location after all danger of frost has passed and nighttime lows are 55F or higher. Continue watering regularly, keeping the soil moist but not soggy. Increase the frequency of fertilizing to every two-three weeks.

Frequent pruning will be required to keep the plant bushy and compact. Each time a new shoot gets four-five inches long, just pinch off the growing tip. Pinching forces the plant to branch, creating the bushy look it had when you bought it. Do not pinch off any growths after September 1.

This is the most critical period. Decreasing hours of daylight and increasing nighttime hours cause poinsettias to set buds that produce flowers. (Note: What look like brightly colored flowers are really leaves. The flowers are the yellow buds within the colored leaves.) Starting October 1, plants must have complete darkness for 14 hours every night. It is this long period of darkness that causes the leaves to change colors. Homeowners have tried a variety of ingenious ways to accomplish this – from putting them in a closet to covering them with a box. Use whatever “trick” works for you.  But, be aware that any stray light from a street or household lamp or other source could delay or stop the color-changing process.

From October to December, give the plants strong light (this is what gives the leaves their bright color) but do not keep them outdoors if the temperature falls below 60F. Continue watering and fertilizing them as you did in the summer. If all goes well, the plants should flower in 8-10 weeks, just in time for the holidays.